JP2959553B2 - Handoff method and mobile terminal - Google Patents
Handoff method and mobile terminalInfo
- Publication number
- JP2959553B2 JP2959553B2 JP10117440A JP11744098A JP2959553B2 JP 2959553 B2 JP2959553 B2 JP 2959553B2 JP 10117440 A JP10117440 A JP 10117440A JP 11744098 A JP11744098 A JP 11744098A JP 2959553 B2 JP2959553 B2 JP 2959553B2
- Authority
- JP
- Japan
- Prior art keywords
- mobile terminal
- base station
- base stations
- frequency
- mobile
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Mobile Radio Communication Systems (AREA)
- Radio Transmission System (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は自動車電話システム
のように複数の基地局間を端末が移動しても継続して通
信路を提供する移動通信システムのハンドオフ（基地局
切り換え）方法及びそれを実現する移動端末に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handoff (base station switching) method for a mobile communication system which provides a communication path continuously even when a terminal moves between a plurality of base stations, such as a mobile telephone system, and a method thereof. The mobile terminal to be realized.
【０００２】[0002]
【従来の技術】自動車電話システムのように複数の基地
局で異なったサービスエリアをカバーしているいわゆる
セル方式の移動通信システムにおいて、通話中に移動端
末が移動するために通信する基地局を切り換えて通話を
継続させるハンドオフは必須の技術であり、この品質を
高めることは重要な課題となっている。ハンドオフの品
質を高める方法としては、図３に示すようにセルの境界
において複数の基地局から同一の端末に対して異なる周
波数で同時に信号を送信するとともに、移動端末が送信
する信号を複数の基地局で受信し、交換局においてダイ
バーシチ合成を行うハンドオフ方法がある。この方法は
「移動通信システムのハンドオフ方法及び移動受信機」
（特願平２−２９４１８２号）に詳述されている。2. Description of the Related Art In a so-called cellular mobile communication system in which a plurality of base stations cover different service areas, such as an automobile telephone system, a base station with which a mobile terminal communicates to switch during a call is switched. Handoff, in which calls are continued, is an indispensable technology, and improving this quality is an important issue. As a method for improving the quality of handoff, as shown in FIG. 3, signals are transmitted simultaneously from a plurality of base stations to the same terminal at different frequencies at the cell boundary, and a signal transmitted by the mobile terminal is transmitted to a plurality of base stations. There is a handoff method in which reception is performed by a station and diversity combining is performed in an exchange. This method is described as "Handoff method and mobile receiver of mobile communication system".
(Japanese Patent Application No. 2-294182).
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、各々の
周波数に複数のチャネルが時分割多重されている通信方
式において、従来のハンドオフ方法を実現するためには
基地局が周囲のセルにおいて移動端末が用いる送信周波
数をすべて受信できる必要があるため、それぞれの基地
局は自局のセルの周波数の数の受信機の他に、周囲のセ
ルの周波数を受信するために数倍の受信機をもつ必要が
あるという問題点がある。第一の発明の目的は上述の従
来のハンドオフ方法の問題点を軽減し、従来のハンドオ
フ方法の効果を損なうことなく、基地局がもつ必要があ
る受信機の数を減らすことができるハンドオフ方法及び
それを実現する移動端末を提供することにある。However, in a communication system in which a plurality of channels are time-division multiplexed on each frequency, in order to realize a conventional handoff method, a base station is used by a mobile terminal in a surrounding cell. Since it is necessary to be able to receive all transmission frequencies, each base station needs to have several times the number of receivers to receive the frequency of the surrounding cells in addition to the number of receivers of its own cell frequency. There is a problem that there is. An object of the first invention is to alleviate the above-mentioned problems of the conventional handoff method, and to reduce the number of receivers that the base station needs to have without impairing the effect of the conventional handoff method. It is to provide a mobile terminal that realizes this.
【０００４】この第一の発明のハンドオフ方法は一部の
周波数を隣接基地局共通に割り当て、セルの境界に近づ
いた移動端末のチャネルを限られた隣接基地局共通な周
波数に収容することにより基地局で受信すべき周波数を
減らす方法であるが、この方法ではダイバーシチ合成の
開始を基地局側で判定しようとすると、移動端末の送信
信号を複数の基地局で受信してダイバーシチ合成をする
前後で、複数の基地局において移動端末の信号の受信レ
ベルを測定する必要があるため、ダイバーシチ合成をし
ないより広い範囲で隣接基地局共通な周波数を設定する
必要があり、したがって基地局で用意する必要がある受
信機の数が十分に少なくできないという問題点がある。
第二の発明の目的はこの問題点を解決し、基地局で用意
する必要がある受信機の数をさらに少なくできるハンド
オフ方法及びそれを実現する移動端末を提供することに
ある。The handoff method according to the first aspect of the present invention allocates some frequencies in common to adjacent base stations, and accommodates a channel of a mobile terminal approaching a cell boundary in a limited common base station common frequency. In this method, the frequency to be received by the station is reduced.However, in this method, when the base station side attempts to determine the start of diversity combining, the transmission signal of the mobile terminal is received by a plurality of base stations and before and after performing diversity combining. Since it is necessary to measure the reception level of the signal of the mobile terminal in a plurality of base stations, it is necessary to set a common frequency for adjacent base stations in a wider range without performing diversity combining, and thus it is necessary to prepare in the base station There is a problem that the number of certain receivers cannot be reduced sufficiently.
It is an object of the second invention to solve this problem and to provide a handoff method that can further reduce the number of receivers that need to be prepared at the base station, and a mobile terminal that realizes the method.
【０００５】[0005]
【課題を解決するための手段】以上の課題を解決するた
めに、本発明のハンドオフ方法は、複数の基地局間を移
動する移動端末に対して通信路を逐次変更して継続的に
通信路を提供する移動通信システムにて、移動端末が複
数の基地局と通信可能な位置にあるときにそれぞれの基
地局は移動端末からの信号を同時に受信してダイバーシ
チ合成をするハンドオフ方法であって、複数の周波数が
隣接する基地局に共通に割り当ててあり、移動端末が位
置する場所に応じて前記隣接する基地局共通に割り当て
られた複数の周波数のうちいずれか一つを移動端末の送
信周波数として用いることを特徴としている。また、本
発明の移動端末は、複数の基地局間を移動する移動端末
に対して通信路を逐次変更して継続的に通信路を提供
し、移動端末が複数の基地局と通信可能な位置にあると
きにそれぞれの基地局は移動端末からの信号を同時に受
信してダイバーシチ合成をする移動通信システムにおけ
る移動端末において、複数の周波数が隣接する基地局に
共通に割り当ててあり、移動端末が位置する場所に応じ
て前記隣接する基地局共通に割り当てられた複数の周波
数のうちいずれか一つの周波数にて信号を送信する手段
を含んで構成されることを特徴としている。また、本発
明の移動端末は、複数の基地局間を移動する移動端末に
対して通信路を逐次変更して継続的に通信路を提供し、
移動端末が複数の基地局と通信可能な位置にあるときに
それぞれの基地局は移動端末からの信号を同時に受信し
てダイバーシチ合成をする移動通信システムにおける移
動端末において、少なくとも一つの周波数が隣接する基
地局に共通に割り当ててあり、複数の基地局と通信がで
きる場所に位置するとき前記隣接する基地局共通に割り
当てられた周波数にて信号を送信する手段を含んで構成
されることを特徴としている。In order to solve the above-mentioned problems, a handoff method according to the present invention provides a method for continuously changing a communication path for a mobile terminal moving between a plurality of base stations by continuously changing the communication path. In the mobile communication system that provides, when the mobile terminal is in a position capable of communicating with a plurality of base stations, each base station is a handoff method of simultaneously receiving signals from the mobile terminal and performing diversity combining, A plurality of frequencies are commonly assigned to adjacent base stations, and any one of the plurality of frequencies commonly assigned to the adjacent base station according to the location where the mobile terminal is located is used as the transmission frequency of the mobile terminal. It is characterized in that it is used. Further, the mobile terminal of the present invention continuously changes the communication path for mobile terminals moving between a plurality of base stations to provide a continuous communication path, so that the mobile terminal can communicate with a plurality of base stations. In a mobile terminal in a mobile communication system in which a base station receives signals from mobile terminals simultaneously and performs diversity combining, a plurality of frequencies are commonly assigned to adjacent base stations, and the mobile terminal And means for transmitting a signal at any one of a plurality of frequencies assigned to the adjacent base stations in accordance with the location where the communication is performed. Further, the mobile terminal of the present invention continuously provides a communication path by sequentially changing the communication path for the mobile terminal moving between a plurality of base stations,
When the mobile terminal is at a position where it can communicate with a plurality of base stations, each base station receives signals from the mobile terminal simultaneously and performs diversity combining in the mobile terminal in the mobile communication system, at least one frequency is adjacent. Commonly allocated to the base station, characterized in that it comprises means for transmitting a signal at a frequency commonly allocated to the adjacent base station when located in a place that can communicate with a plurality of base stations I have.
【０００６】また、本発明の移動端末は、複数の基地局
間を移動する移動端末に対して通信路を逐次変更して継
続的に通信路を提供し、移動端末が複数の基地局と通信
可能な位置にあるときにそれぞれの基地局は移動端末か
らの信号を同時に受信してダイバーシチ合成をする移動
通信システムにおける移動端末において、少なくとも一
つの周波数が隣接する基地局に共通に割り当ててあり、
当該移動端末が位置する場所に応じて前記隣接する基地
局共通に割り当てられた周波数にて信号を送信する手段
を含んで構成されることを特徴としている。また、本発
明の移動端末は、複数の基地局間を移動する移動端末に
対して通信路を逐次変更して継続的に通信路を提供し、
移動端末が複数の基地局と通信可能な位置にあるときに
それぞれの基地局は移動端末からの信号を同時に受信し
てダイバーシチ合成をする移動通信システムにおける移
動端末において、少なくとも一つの周波数が隣接する基
地局に共通に割り当ててあり、周囲の基地局からの信号
の受信レベルを測定する手段と、前記受信レベルに基づ
いて前記ダイバーシチ合成の開始と終了を判断する手段
と、前記開始と終了の際には移動端末の送信周波数の切
り替えを該基地局に通知する手段と、前記ダイバーシチ
合成をしている間に限り前記隣接基地局共通に割り当て
られた周波数を用いて信号を送信する手段とを含んで構
成されることを特徴としている。Further, the mobile terminal of the present invention continuously provides a communication path by sequentially changing a communication path for a mobile terminal moving between a plurality of base stations, and the mobile terminal communicates with the plurality of base stations. When in a possible position, each base station receives a signal from the mobile terminal at the same time, and in a mobile terminal in a mobile communication system that performs diversity combining, at least one frequency is commonly assigned to an adjacent base station,
The mobile terminal is characterized in that it includes means for transmitting a signal at a frequency assigned commonly to the adjacent base stations according to the location where the mobile terminal is located. Further, the mobile terminal of the present invention continuously provides a communication path by sequentially changing the communication path for the mobile terminal moving between a plurality of base stations,
When the mobile terminal is at a position where it can communicate with a plurality of base stations, each base station receives signals from the mobile terminal simultaneously and performs diversity combining in the mobile terminal in the mobile communication system, at least one frequency is adjacent. Means commonly assigned to base stations, means for measuring the reception level of signals from surrounding base stations, means for determining the start and end of the diversity combining based on the reception level, and Including means for notifying the base station of the switching of the transmission frequency of the mobile terminal, and means for transmitting a signal using a frequency that is commonly assigned to the adjacent base station as long as the diversity combining is performed It is characterized by comprising.
【０００７】そして、本発明においては、セルの境界に
近づいた移動端末の送信信号だけを複数の基地局で受信
する。このとき基地局で受信すべき周波数を減らすため
には、セルの境界に近づいた移動端末のチャネルを限ら
れた特定の周波数に収容し、これらの周波数だけを複数
の基地局で受信可能となるようにすればよい。このよう
にすることによってセル全体で使われる周波数の数が多
くても、それぞれの基地局が受信すべき周波数は自局の
セル内の端末が使用するものの他には、限られた周波数
だけを受信できればよいので、それぞれの基地局で必要
な受信機の数を減らすことができる。[0007] In the present invention, only a transmission signal of a mobile terminal approaching a cell boundary is received by a plurality of base stations. At this time, in order to reduce the frequency to be received by the base station, the channel of the mobile terminal approaching the cell boundary is accommodated in a limited specific frequency, and only these frequencies can be received by a plurality of base stations. What should I do? In this way, even if the number of frequencies used in the entire cell is large, the frequencies to be received by each base station are limited to those used by the terminals in the cell of the own station. Since it is only necessary to be able to receive, the number of receivers required in each base station can be reduced.
【０００８】また、本発明においては、移動端末は周囲
の基地局からの信号の受信レベルを測定することによっ
て、ダイバーシチ受信が必要ない間は常に基地局固有に
割り当てられた周波数を利用できる。そして移動端末が
測定する周囲の基地局からの信号の受信レベルが下が
り、ダイバーシチ受信が必要になった瞬間に移動端末の
送信周波数を隣接基地局共通の周波数に切り換える。こ
のようにすることによって隣接基地局共通の周波数を用
いる場所は複数の基地局で移動端末の信号を受信してダ
イバーシチ合成する間に限定できるので、隣接基地局共
通の周波数は少なくてすむから、基地局に必要な受信機
の数をさらに少なくできる。Further, in the present invention, the mobile terminal measures the reception level of a signal from a surrounding base station, so that the mobile terminal can always use the frequency assigned uniquely to the base station while diversity reception is not required. Then, at the moment when the reception level of the signal from the surrounding base station measured by the mobile terminal decreases and the diversity reception becomes necessary, the transmission frequency of the mobile terminal is switched to the common frequency of the adjacent base station. By doing so, the location using the common frequency of the adjacent base station can be limited during the diversity combining by receiving the signal of the mobile terminal at a plurality of base stations, so the common frequency of the adjacent base station can be reduced, The number of receivers required for the base station can be further reduced.
【０００９】[0009]
【発明の実施の形態】次に図面を参照して本発明につい
て詳細に説明する。図１に第一の発明のハンドオフの手
順の実施形態を示す。いま、移動端末（３０ａ，３０
ｂ）が基地局１（１０）のある地点Ｘを出発して基地局
２（２０）のある地点Ｙまで移動する場合を考える。な
お、基地局から移動端末への送信方法は本発明の範囲外
であるが一実施形態として記す。地点Ｘから地点Ａまで
は基地局１に十分近く、基地局２からの信号は受信され
ないので移動端末は基地局１に固有に割り当てられた周
波数ｆ１を送信し、基地局１がこれを周波数ｆ１用の受
信機（１２）により受信し、基地局１は周波数Ｆ１を送
信することで通常の通信が行われている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of a handoff procedure according to the first invention. Now, the mobile terminals (30a, 30
Consider a case in which b) moves from a certain point X of the base station 1 (10) to a certain point Y of the base station 2 (20). The transmission method from the base station to the mobile terminal is out of the scope of the present invention, but will be described as one embodiment. From the point X to the point A, it is sufficiently close to the base station 1 and a signal from the base station 2 is not received. Therefore, the mobile terminal transmits a frequency f1 uniquely assigned to the base station 1, and the base station 1 transmits the frequency f1. The base station 1 performs reception by transmitting the frequency F1.
【００１０】移動端末が地点Ａを通過すると基地局１か
らの信号の受信レベルが低下するので他の基地局とも回
線を設定するために移動端末の送信信号が他の基地局に
おいても受信出来るように移動端末の送信周波数を隣接
基地局共通に割り当てられた周波数ｆｍ１に切り換え
る。基地局１はこれを周波数ｆｍ１用の受信機１３で受
信する。基地局１から移動端末への送信周波数もＦｍ１
に切り換える。When the mobile terminal passes through point A, the reception level of the signal from base station 1 decreases, so that the transmission signal of the mobile terminal can be received by another base station in order to set up a line with another base station. Then, the transmission frequency of the mobile terminal is switched to the frequency fm1 commonly assigned to the adjacent base station. The base station 1 receives this at the receiver 13 for the frequency fm1. The transmission frequency from the base station 1 to the mobile terminal is also Fm1
Switch to.
【００１１】移動端末が地点Ｂを通過するとさらに基地
局１からの信号の受信レベルが低下し、基地局２におい
ても周波数ｆｍ１用の受信機２４を用いて移動端末の信
号を受信できるようになるため基地局２とも回線を設定
する。移動端末からの信号（周波数ｆｍ１）は基地局１
の周波数ｆｍ１用の受信機１３及び基地局２の周波数ｆ
ｍ１用の受信機２４で受信され、図３に示すような交換
局へ送られ、そこでダイバーシチ合成される。基地局１
の送信周波数はＦｍ１のままで基地局２から移動端末へ
はＦｍ２を使って送信する。移動端末は周波数Ｆｍ１及
びＦｍ２を受信してダイバーシチ合成する。When the mobile terminal passes through the point B, the reception level of the signal from the base station 1 further decreases, and the base station 2 can receive the signal of the mobile terminal using the receiver 24 for the frequency fm1. Therefore, a line is set with the base station 2. A signal (frequency fm1) from the mobile terminal is transmitted to the base station 1
Receiver 13 for frequency fm1 and frequency f of base station 2
The signal is received by the m1 receiver 24 and sent to an exchange as shown in FIG. 3, where it is diversity-combined. Base station 1
Is transmitted from the base station 2 to the mobile terminal using Fm2 while keeping the transmission frequency of Fm1. The mobile terminal receives the frequencies Fm1 and Fm2 and performs diversity combining.
【００１２】移動端末が地点Ｃを過ぎると、移動端末の
信号の受信レベルが基地局２の方が高くなるので、移動
端末は送信周波数を隣接基地局共通の周波数ｆｍ２に切
り換える。この時基地局１は移動端末との通信を切断せ
ずに周波数ｆｍ２用の受信機１４を用いて周波数ｆｍ２
を受信するとともに周波数Ｆｍ１で送信し続ける。基地
局２は周波数ｆｍ２用の受信機２３を用いて受信する。
このようにして依然ダイバーシチ合成を基地局、移動端
末双方で続ける。When the mobile terminal passes point C, the reception level of the signal of the mobile terminal becomes higher in base station 2, so that the mobile terminal switches the transmission frequency to frequency fm2 common to the adjacent base stations. At this time, the base station 1 uses the frequency fm2 receiver 14 without disconnecting the communication with the mobile terminal and uses the frequency fm2.
And continues transmitting at the frequency Fm1. The base station 2 receives using the receiver 23 for the frequency fm2.
In this way, diversity combining is still continued at both the base station and the mobile terminal.
【００１３】移動端末が地点Ｄを過ぎると基地局２にお
ける移動端末の信号の受信レベルが上がるので、基地局
１は送受信をやめて、移動端末は基地局２とのみ通信を
続ける。地点Ｄと地点Ｅの間は移動端末がＵターンする
などして再び基地局１に近づく可能性があるので、隣接
基地局共通の周波数を使い続ける。When the mobile terminal passes point D, the reception level of the signal of the mobile terminal at base station 2 increases, so that base station 1 stops transmitting and receiving, and the mobile terminal continues to communicate with base station 2 only. Since there is a possibility that the mobile terminal approaches the base station 1 again by making a U-turn between the points D and E, the common frequency of the adjacent base station is continuously used.
【００１４】地点Ｅを過ぎると基地局２の受信レベルが
高くなるので、移動端末は送信周波数を基地局２に固有
に割り当てられた周波数ｆ２に切り換え、基地局は周波
数ｆ２用の受信機２２を用いて受信する。これに合わせ
て基地局２の送信周波数もＦ２に切り換える。Since the reception level of the base station 2 increases after the point E, the mobile terminal switches the transmission frequency to the frequency f2 uniquely assigned to the base station 2, and the base station switches the receiver 22 for the frequency f2. Receive using. At the same time, the transmission frequency of the base station 2 is also switched to F2.
【００１５】図４は基地局装置の構成の一例を示す図で
ある。アンテナ５０で受信された信号はアンテナ共用装
置６０と増幅回路８０を介して、自局に固有に割り当て
られた周波数用の受信回路９０、隣接基地局共通で、自
局に近い範囲で用いる周波数用の受信回路９１、隣接基
地局共通で他局に近い範囲で用いる周波数用の受信回路
９２へ送られる。そして受信回路９１の出力は端子１０
３，１０４から入力される他局で受信された同じ移動端
末の信号と合成回路１１０でダイバーシチ合成される。
受信回路９２の出力は端子１０１，１０２を通して他の
合成回路へ送られる。FIG. 4 is a diagram showing an example of the configuration of the base station device. The signal received by the antenna 50 is transmitted to the receiving circuit 90 for the frequency uniquely assigned to the own station via the antenna sharing device 60 and the amplifier circuit 80, and to the frequency common to the adjacent base station and used in a range close to the own station. The receiving circuit 91 is sent to a receiving circuit 92 for a frequency which is common to adjacent base stations and used in a range close to other stations. The output of the receiving circuit 91 is the terminal 10
Diversity combining is performed by combining circuit 110 with the signal of the same mobile terminal received by another station and input from 3 and 104.
The output of the receiving circuit 92 is sent to other combining circuits through terminals 101 and 102.
【００１６】なお本実施形態で述べたダイバーシチ合成
をどのように行うかや、どういう条件になったら地点
Ａ，Ｂ，Ｃ，Ｄ，Ｅのようにハンドオフの処理を行うか
は本発明の範囲外であり、どの様な方法を用いてもよい
ことは明らかである。It is out of the scope of the present invention how the diversity combining described in the present embodiment is performed and under what conditions the handoff processing is performed at points A, B, C, D and E. It is clear that any method may be used.
【００１７】第二の発明では移動端末は周囲の基地局か
らの信号の受信レベルを測定することが前提となってい
るが、その一つの手段をまず説明する。移動端末と基地
局は同一周波数上に時分割多重されている複数の通話チ
ャネルのうち１つを使って通信する。別の周波数上には
複数の制御チャネルが時分割多重されており、相互に干
渉する基地局同士は相異なる制御チャネルを使って制御
情報を流している。制御チャネルと通話チャネルの多重
度は相異なるように設定すると、移動端末は通信の空き
時間を利用して、制御チャネルを監視することにより周
囲の全ての基地局からの受信信号レベルを測定できる。
この方法は金井，武次，古谷，近藤「ディジタル移動通
信用高速ハンドオフ方式実験システム」（電子情報通信
学会技術研究報告ＲＣＳ８９−３７）に詳述されてい
る。The second invention is based on the premise that the mobile terminal measures the reception level of a signal from a surrounding base station. One means will be described first. The mobile terminal and the base station communicate using one of a plurality of communication channels time-division multiplexed on the same frequency. A plurality of control channels are time-division multiplexed on different frequencies, and base stations that interfere with each other transmit control information using different control channels. If the multiplicity of the control channel and that of the communication channel are set to be different from each other, the mobile terminal can measure the received signal levels from all the surrounding base stations by monitoring the control channel using the idle time of communication.
This method is described in detail in Kanai, Takeji, Furuya, and Kondo, "Experimental System for High-Speed Handoff Method for Digital Mobile Communication" (IEICE Technical Report RCS89-37).
【００１８】図２に第二の発明のハンドオフの手順の実
施形態を示す。いま、移動端末（３０ａ，３０ｂ）が基
地局１（１０）のある地点Ｘを出発して基地局２（２
０）のある地点Ｙまで移動する場合を考える。なお、基
地局から移動端末への送信方法は本発明の範囲外である
が一実施形態として記す。FIG. 2 shows an embodiment of a handoff procedure according to the second invention. Now, the mobile terminal (30a, 30b) departs from a certain point X of the base station 1 (10), and moves to the base station 2 (2
Consider a case in which the user moves to a certain point Y at 0). The transmission method from the base station to the mobile terminal is out of the scope of the present invention, but will be described as one embodiment.
【００１９】地点Ｘから地点Ｂまでは基地局１に近く，
基地局１と移動端末の間の信号の受信レベルは高いの
で、移動端末は基地局１固有に割り当てられた周波数ｆ
１を送信し、基地局１がこれを周波数ｆ１用の受信機
（１２）により受信し、基地局１は周波数Ｆ１を送信す
ることで通常の通信が行われている。このとき移動端末
は周囲の基地局からの信号の受信レベルを測定してい
る。移動端末が地点Ｂに近づくと基地局１からの信号の
受信レベルが低下し、基地局２の受信レベルが高くな
る。From point X to point B is close to base station 1,
Since the reception level of the signal between the base station 1 and the mobile terminal is high, the mobile terminal receives the frequency f assigned uniquely to the base station 1.
1 is transmitted, the base station 1 receives it by the receiver for frequency f1 (12), and the base station 1 performs normal communication by transmitting the frequency F1. At this time, the mobile terminal is measuring the reception level of a signal from a surrounding base station. When the mobile terminal approaches point B, the reception level of the signal from base station 1 decreases and the reception level of base station 2 increases.
【００２０】移動端末が地点Ｂを通過するとさらに基地
局１からの信号の受信レベルが低下し、基地局２におい
ても移動端末の信号を受信できるようになるため、ダイ
バーシチ合成の開始を判断し、周波数切り替えを基地局
１，基地局２に通知して、移動端末の送信周波数を基地
局１と基地局２共通に割り当てられている周波数ｆｍ１
に切り換える。基地局から移動端末への送信周波数もＦ
ｍ１に切り換える。移動端末からの信号ｆｍ１は基地局
１の周波数ｆｍ１用の受信機１３及び基地局２の周波数
ｆｍ１用の受信機２４で送信され、図３に示すような交
換局へ送られ、そこでダイバーシチ合成される。基地局
１は送信周波数Ｆｍ１で送信し、基地局２も移動端末へ
Ｆｍ２を使って送信を始める。移動端末は周波数Ｆｍ１
及びＦｍ２を受信してダイバーシチ合成する。When the mobile terminal passes through the point B, the reception level of the signal from the base station 1 further decreases, and the base station 2 can receive the signal of the mobile terminal. Therefore, the start of diversity combining is determined. The base station 1 and the base station 2 are notified of the frequency switching, and the transmission frequency of the mobile terminal is set to the frequency fm1 assigned to both the base station 1 and the base station 2.
Switch to. The transmission frequency from the base station to the mobile terminal is also F
Switch to m1. The signal fm1 from the mobile terminal is transmitted by the receiver 13 for the frequency fm1 of the base station 1 and the receiver 24 for the frequency fm1 of the base station 2, and is sent to an exchange as shown in FIG. 3, where it is subjected to diversity combining. You. The base station 1 transmits at the transmission frequency Fm1, and the base station 2 also starts transmitting to the mobile terminal using Fm2. The mobile terminal has the frequency Fm1
And Fm2 to perform diversity combining.
【００２１】移動端末が地点Ｃを過ぎると、移動端末の
信号の受信レベルが基地局２の方が高くなるので、移動
端末は送信周波数を隣接基地局共通の周波数ｆｍ２に切
り換える。この時基地局１は移動端末との通信を切断せ
ずに周波数ｆｍ２用の受信機１４を用いて周波数ｆｍ２
を受信するとともに周波数Ｆｍ１で送信し続ける。基地
局２は周波数ｆｍ２用の受信機２３を用いて受信する。
このようにして依然ダイバーシチ合成を基地局，移動端
末双方で続ける。When the mobile terminal passes point C, the reception level of the signal of the mobile terminal becomes higher in the base station 2, so that the mobile terminal switches the transmission frequency to the frequency fm2 common to the adjacent base stations. At this time, the base station 1 uses the frequency fm2 receiver 14 without disconnecting the communication with the mobile terminal and uses the frequency fm2.
And continues transmitting at the frequency Fm1. The base station 2 receives using the receiver 23 for the frequency fm2.
In this way, diversity combining is still continued at both the base station and the mobile terminal.
【００２２】移動端末が地点Ｄを過ぎると基地局２にお
ける移動端末の信号の受信レベルが上がるので、ダイバ
ーシチ合成の終了を判断し，これを基地局１，基地局２
に通知する。そして基地局１は送受信をやめて、移動端
末は送信周波数を基地局２固有に割り当てられた周波数
ｆ２に切り換え、基地局２は周波数ｆ２用の受信機２２
を用いて受信し、移動端末は基地局２とのみ通信を続け
る。基地局２から移動端末への送信周波数も同時にＦ２
に切り換える。なお、このときも移動端末はＵターンす
るなどして再び基地局１に近づく可能性があるので、周
囲の基地局からの信号の受信レベルを測定している。When the mobile terminal passes the point D, the reception level of the signal of the mobile terminal at the base station 2 increases. Therefore, the end of the diversity combining is determined, and this is determined by the base station 1, base station 2
Notify. Then, the base station 1 stops transmission / reception, the mobile terminal switches the transmission frequency to the frequency f2 uniquely assigned to the base station 2, and the base station 2 operates the receiver 22 for the frequency f2.
, And the mobile terminal continues to communicate only with the base station 2. The transmission frequency from the base station 2 to the mobile terminal is also F2
Switch to. At this time, since the mobile terminal may approach the base station 1 again by making a U-turn or the like, the reception level of a signal from a surrounding base station is measured.
【００２３】なお本実施形態で述べたダイバーシチ合成
をどのように行うかや、どういう条件になったら地点
Ｂ，Ｃ，Ｄのようにハンドオフの処理を行うかは本発明
の範囲外であり、どの様な方法を用いてもよいことは明
らかである。It is out of the scope of the present invention how the diversity combining described in the present embodiment is performed and under what conditions the handoff processing is performed at points B, C and D. Obviously, such a method may be used.
【００２４】[0024]
【発明の効果】本発明のハンドオフ方法を用いない場合
には移動端末の送信信号を複数の基地局で同時に受信す
るために周囲の基地局で使われる周波数をすべて受信で
きる必要があるので、非常に多くの受信回路が基地局に
必要である。ところが以上詳細に説明したハンドオフ方
法によれば自局のセルを出入りする移動端末のために図
４のように隣接基地局共通な周波数用の受信回路９１，
９２だけを基地局に設ければよいので、基地局の受信回
路の数を大幅に削減できる。In the case where the handoff method of the present invention is not used, it is necessary to be able to receive all the frequencies used by the surrounding base stations in order to simultaneously receive the transmission signal of the mobile terminal by a plurality of base stations. Many receiving circuits are required for the base station. However, according to the handoff method described in detail above, a receiving circuit 91 for a frequency common to adjacent base stations as shown in FIG.
Since only 92 need be provided in the base station, the number of receiving circuits in the base station can be greatly reduced.
【００２５】また、本発明のハンドオフ方法によれば、
ダイバーシチ受信が必要ない間は常に各基地局固有に割
り当てられた周波数を利用でき、ダイバーシチ受信が必
要な間に限り移動端末の送信周波数として隣接基地局共
通の周波数を用いるので、隣接基地局共通の周波数は少
なくてすむ。従って図４にある隣接基地局共通の周波数
用の受信回路９１，９２の数が少なくできるので、基地
局装置の受信回路の数をさらに削減できる。According to the handoff method of the present invention,
As long as diversity reception is not required, the frequency assigned uniquely to each base station can be used at all times.As long as diversity reception is required, a common frequency for the adjacent base station is used as the transmission frequency of the mobile terminal. Fewer frequencies are required. Accordingly, the number of receiving circuits 91 and 92 for frequencies common to adjacent base stations shown in FIG. 4 can be reduced, so that the number of receiving circuits of the base station apparatus can be further reduced.
【図１】 第一の発明の動作を説明する図。FIG. 1 is a diagram for explaining the operation of the first invention.
【図２】 第二の発明の動作を説明する図。FIG. 2 is a diagram illustrating the operation of the second invention.
【図３】 従来の技術で基地局、移動端末双方でダイバ
ーシチ受信を行う様子を示す図。FIG. 3 is a diagram showing a situation in which both a base station and a mobile terminal perform diversity reception according to a conventional technique.
【図４】 本発明で使われる基地局装置の１構成例を示
す図。FIG. 4 is a diagram showing a configuration example of a base station device used in the present invention.
１０，２０ 基地局 １１，２１ アンテナ １２，２２ 自局に固有に割り当てられた周波数用の受
信機 １３，１４，２３，２４ 共通に割り当てられた周波
数用の受信機 ３０ａ，３０ｂ 移動端末 ３０ 移動端末 ４０ 交換局 ５０ アンテナ ６０ アンテナ共用装置 ７０ 送信回路 ８０ 増幅回路 ９０ 自局に固有に割り当てられた周波数用の受信回路 ９１ 隣接基地局共通で自局に近い範囲で用いる周波数
用の受信回路 ９２ 隣接基地局共通で他局に近い範囲で用いる周波数
用の受信回路 １１０ 合成回路 １２０ 基地局制御装置10,20 Base station 11,21 Antenna 12,22 Receiver for frequency uniquely assigned to own station 13,14,23,24 Receiver for frequency commonly assigned 30a, 30b Mobile terminal 30 Mobile terminal Reference Signs List 40 switching station 50 antenna 60 antenna sharing device 70 transmitting circuit 80 amplifying circuit 90 receiving circuit for frequency uniquely assigned to own station 91 receiving circuit for frequencies common to adjacent base stations and used in a range near own station 92 adjacent base Frequency receiving circuit common to stations and used in a range close to other stations 110 Combining circuit 120 Base station controller
───────────────────────────────────────────────────── フロントページの続き (72)発明者 武次 将徳 東京都港区芝五丁目７番１号 日本電気 株式会社内 (56)参考文献 特開 平３−188719（ＪＰ，Ａ) 特開 昭62−133833（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) H04B 7/24 - 7/26 H04Q 7/00 - 7/38 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masanori Takeji 5-7-1 Shiba, Minato-ku, Tokyo Within NEC Corporation (56) References JP-A-3-188719 (JP, A) JP-A 62-133833 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) H04B 7/24-7/26 H04Q 7/00-7/38
Claims (5)
して通信路を逐次変更して継続的に通信路を提供する移
動通信システムにて、移動端末が複数の基地局と通信可
能な位置にあるときにそれぞれの基地局は移動端末から
の信号を同時に受信してダイバーシチ合成をするハンド
オフ方法であって、 複数の周波数が隣接する基地局に共通に割り当ててあ
り、 移動端末が位置する場所に応じて前記隣接する基地局共
通に割り当てられた複数の周波数のうちいずれか一つを
移動端末の送信周波数として用いることを特徴としたハ
ンドオフ方法。1. A mobile communication system for continuously providing a communication path by sequentially changing a communication path for a mobile terminal moving between a plurality of base stations so that the mobile terminal can communicate with the plurality of base stations. A handoff method in which each base station simultaneously receives signals from mobile terminals when in a position and performs diversity combining, wherein a plurality of frequencies are commonly assigned to adjacent base stations, and the mobile terminal is located. A handoff method characterized by using any one of a plurality of frequencies commonly assigned to adjacent base stations according to a location as a transmission frequency of a mobile terminal.
して通信路を逐次変更して継続的に通信路を提供し、移
動端末が複数の基地局と通信可能な位置にあるときにそ
れぞれの基地局は移動端末からの信号を同時に受信して
ダイバーシチ合成をする移動通信システムにおける移動
端末において、 複数の周波数が隣接する基地局に共通に割り当ててあ
り、 移動端末が位置する場所に応じて前記隣接する基地局共
通に割り当てられた複数の周波数のうちいずれか一つの
周波数にて信号を送信する手段を含んで構成されること
を特徴とする移動端末。2. A communication path is sequentially provided to a mobile terminal moving between a plurality of base stations by sequentially changing the communication path, and the mobile terminal is located at a position where it can communicate with a plurality of base stations. Each base station receives signals from mobile terminals simultaneously and performs diversity combining. In a mobile terminal, multiple frequencies are commonly assigned to adjacent base stations. A mobile terminal comprising means for transmitting a signal at any one of a plurality of frequencies commonly assigned to said adjacent base stations.
して通信路を逐次変更して継続的に通信路を提供し、移
動端末が複数の基地局と通信可能な位置にあるときにそ
れぞれの基地局は移動端末からの信号を同時に受信して
ダイバーシチ合成をする移動通信システムにおける移動
端末において、 少なくとも一つの周波数が隣接する基地局に共通に割り
当ててあり、 複数の基地局と通信ができる場所に位置するとき前記隣
接する基地局共通に割り当てられた周波数にて信号を送
信する手段を含んで構成されることを特徴とする移動通
信システムにおける移動端末。3. When a communication path is successively provided to a mobile terminal moving between a plurality of base stations by continuously changing the communication path, and the mobile terminal is in a position where it can communicate with a plurality of base stations. Each base station receives signals from the mobile terminals at the same time, and in a mobile terminal in a mobile communication system that performs diversity combining, at least one frequency is commonly assigned to adjacent base stations, and communication with a plurality of base stations is performed. A mobile terminal in a mobile communication system, comprising: means for transmitting a signal at a frequency allocated to the adjacent base station when the mobile terminal is located at a location where the mobile terminal can be located.
して通信路を逐次変更して継続的に通信路を提供し、移
動端末が複数の基地局と通信可能な位置にあるときにそ
れぞれの基地局は移動端末からの信号を同時に受信して
ダイバーシチ合成をする移動通信システムにおける移動
端末において、 少なくとも一つの周波数が隣接する基地局に共通に割り
当ててあり、 当該移動端末が位置する場所に応じて前記隣接する基地
局共通に割り当てられた周波数にて信号を送信する手段
を含んで構成されることを特徴とする移動通信システム
における移動端末。4. When a communication path is successively provided to a mobile terminal moving between a plurality of base stations by sequentially changing the communication path, and the mobile terminal is in a position where it can communicate with a plurality of base stations. In a mobile terminal in a mobile communication system in which each base station simultaneously receives signals from the mobile terminal and performs diversity combining, at least one frequency is commonly assigned to an adjacent base station, and a location where the mobile terminal is located A mobile terminal in a mobile communication system, characterized by including means for transmitting a signal at a frequency commonly assigned to the adjacent base stations according to the following.
して通信路を逐次変更して継続的に通信路を提供し、移
動端末が複数の基地局と通信可能な位置にあるときにそ
れぞれの基地局は移動端末からの信号を同時に受信して
ダイバーシチ合成をする移動通信システムにおける移動
端末において、 少なくとも一つの周波数が隣接する基地局に共通に割り
当ててあり、 周囲の基地局からの信号の受信レベルを測定する手段
と、前記受信レベルに基づいて前記ダイバーシチ合成の
開始と終了を判断する手段と、前記開始と終了の際には
移動端末の送信周波数の切り替えを該基地局に通知する
手段と、前記ダイバーシチ合成をしている間に限り前記
隣接基地局共通に割り当てられた周波数を用いて信号を
送信する手段とを含んで構成されることを特徴とする移
動通信システムにおける移動端末。5. When a mobile terminal moving between a plurality of base stations is sequentially changed in communication path to provide a continuous communication path, and the mobile terminal is in a position where it can communicate with a plurality of base stations. Each base station receives signals from the mobile terminal simultaneously and performs diversity combining in a mobile terminal in a mobile communication system. At least one frequency is commonly assigned to an adjacent base station, and a signal from a surrounding base station is provided. Means for measuring the reception level of the mobile station, means for determining the start and end of the diversity combining based on the reception level, and notifying the base station of the switching of the transmission frequency of the mobile terminal at the time of the start and end. Means, and means for transmitting a signal using a frequency commonly assigned to the adjacent base stations only while the diversity combining is being performed. Mobile terminal in a mobile communication system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10117440A JP2959553B2 (en) | 1998-04-27 | 1998-04-27 | Handoff method and mobile terminal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10117440A JP2959553B2 (en) | 1998-04-27 | 1998-04-27 | Handoff method and mobile terminal |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3057969A Division JP2841900B2 (en) | 1991-02-27 | 1991-02-27 | Handoff method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10257544A JPH10257544A (en) | 1998-09-25 |
| JP2959553B2 true JP2959553B2 (en) | 1999-10-06 |
Family
ID=14711712
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10117440A Expired - Lifetime JP2959553B2 (en) | 1998-04-27 | 1998-04-27 | Handoff method and mobile terminal |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2959553B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4890980B2 (en) * | 2006-07-10 | 2012-03-07 | 日本電気通信システム株式会社 | Wireless communication system, wireless device, communication control method, and communication control program |
-
1998
- 1998-04-27 JP JP10117440A patent/JP2959553B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10257544A (en) | 1998-09-25 |
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